Conventionally, a water-based ink for ink-jet recording is used widely that comprises a coloring agent, water, a water-soluble organic solvent such as a humectant and a penetrant, and a surfactant. As the coloring agent, a water-soluble dye is used widely in terms of height of chroma, abundance of types, good in water solubility, and the like. However, an ink comprising the water-soluble dye is not sufficient in light resistance and water resistance of the recording material recorded using the ink. This problem may be solved by using pigments as the coloring agent. Specifically, an ink comprising pigments is good in light resistance and water resistance of recording material recorded using the ink. Further, in the ink, when an amount of the penetrant is increased, printing quality is improved. However, increase of the penetrant worsens evaporation characteristic of the ink and a compound derived from a material that forms an ink-jet recording apparatus may be eluted into the ink. Examples of the material that forms the ink-jet recording apparatus include a rubber member and an organic material member other than rubber material. Examples of the rubber member include a wiper and a cap. The wiper wipes a nozzle surface of an ink-jet head, for example. The cap blocks off the nozzle surface from the outside world, for example. When a compound derived from the rubber member is eluted into the ink, there is a possibility that the compound is deposited in the ink. When the compound is deposited, for example, a nozzle of the ink-jet head may be clogged. Further, in the ink, when an amount of the pigment (solid content) is increased, printing quality is improved. However, as in the case of the penetrant, increase of the solid content of the pigment worsens evaporation characteristic of the ink and a compound derived from a material that forms an ink-jet recording apparatus may be eluted into the ink. Further, ejection stability of the ink is affected by amounts of the humectant, the penetrant, and the surfactant and it may be worsened in some cases.
In order to solve the problems of the evaporation characteristic and the ejection stability, an ink is proposed, the flow characteristic thereof is controlled by adjusting viscosity. However, this ink does not solve the problem of the elution of the rubber member into the ink.